New satellite measurements of Arctic Ice shocked scientists. Chris Rapley suggests that the warming Arctic is involved in jet stream instability associated with increasing volatility in weather in lower latitudes, such as we are now experiencing. In other words, that gigantic heat dome and the US Great Drought of 2012 are connected to the warming which seemed so far away it was easy to ignore in Texas and Oklahoma. Do I hear the echo of a cruel laugh? Climate Change is just a conspiracy, they said.

"Preliminary analysis of our data indicates that the rate of loss of sea ice volume in summer in the Arctic may be far larger than we had previously suspected,"...

Preliminary results from the European Space Agency's CryoSat-2 probe indicate that 900 cubic kilometres of summer sea ice has disappeared from the Arctic ocean over the past year.

This rate of loss is 50% higher than most scenarios outlined by polar scientists and suggests that global warming, triggered by rising greenhouse gas emissions, is beginning to have a major impact on the region. In a few years the Arctic ocean could be free of ice in summer, triggering a rush to exploit its fish stocks, oil, minerals and sea routes.

The consequences of losing the Arctic's ice coverage, even for only part of the year, could be profound. Without the cap's white brilliance to reflect sunlight back into space, the region will heat up even more than at present. As a result, ocean temperatures will rise and methane deposits on the ocean floor could melt, evaporate and bubble into the atmosphere. Scientists have recently reported evidence that methane plumes are now appearing in many areas.

Professor Chris Rapley of UCL said: "With the temperature gradient between the Arctic and equator dropping, as is happening now, it is also possible that the jet stream in the upper atmosphere could become more unstable. That could mean increasing volatility in weather in lower latitudes, similar to that experienced this year."

... the shrinking of sea-ice coverage we have observed... is telling us that something highly significant is happening to Earth.

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... over the last three decades, satellites have observed a 13% decline per decade in the summertime minimum.

The thickness of the sea ice is also declining, so overall the ice volume has fallen far - although estimates vary about the actual figure.

Professor Peter Wadhams, from Cambridge University, told BBC News: "A number of scientists who have actually been working with sea ice measurement had predicted some years ago that the retreat would accelerate and that the summer Arctic would become ice-free by 2015 or 2016."

"I was one of those scientists - and of course bore my share of ridicule for daring to make such an alarmist prediction."

"Measurements from submarines have shown that it has lost at least 40% of its thickness since the 1980s, and if you consider the shrinkage as well it means that the summer ice volume is now only 30% of what it was in the 1980s," he added. [emphasis mine]

Joe Romm also give a nice explanation of how it connects to Northern Hemisphere extreme climate events.

But what happens in the Arctic, doesn’t stay in the Arctic. The rapid disappearance of sea ice cover can have consequences that are felt all over the Northern Hemisphere, due to the effects it has on atmospheric patterns. As the ice pack becomes smaller ever earlier into the melting season, more and more sunlight gets soaked up by dark ocean waters, effectively warming up the ocean. The heat and moisture that are then released to the atmosphere in fall and winter could be leading to disturbances of the jet stream, the high-altitude wind that separates warm air to its south from cold air to the north. A destabilized jet stream becomes more ‘wavy’, allowing frigid air to plunge farther south, a possible factor in the extreme winters that were experienced all around the Northern Hemisphere in recent years. Another side-effect is that as the jet stream waves become larger, they slow down or even stall at times, leading to a significant increase in so-called blocking events. These cause extreme weather simply because they lead to unusually prolonged conditions of one type or another. The recent prolonged heatwave, drought and wildfires in the USA are one example of what can happen; another is the cool, dull and extremely wet first half of summer 2012 in the UK and other parts of Eurasia. [emphasis mine]

We also need to discuss how the melting Arctic glaciers will effect sea level rise.

Greenland, especially, was melting at unprecedented rates this spring and summer. Greenland, which is reality a mile-thick glacier of approximately 100,000 year old ice covering 3 islands, could have globally devastating consequences as it melts. It would raise global sea levels by 7 metres (23 feet). That would be the end of coastal cities and other coastal regions. Most of the world's population lives in the zones which would be permanently under the water.

Note too, that Greenland would not be the only ice sheet that melts significantly. There are other, smaller ice sheets in the Arctic, as well as the ice sheet which covers most of Antarctica. If those melt too, much of the land upon which humans live or grow crops would be under the ocean.

The 2012 record Summer Arctic Sea ice melt has staggering implications. Scientists now predict Summer Arctic Sea ice it will disappear all together in Summer in as little as 20 years. According to Nick Toberg when that happens it will have the same warming effect as 20 years of CO2 emissions at the current rate.

The Cambridge University Sea ice researcher Nick Toberg... said: "This is staggering. It's disturbing, scary that we have physically changed the face of the planet. We have about 4m sq km of sea ice. If that goes in the summer months that's about the same as adding 20 years of CO2 at current [human-caused] rates into the atmosphere. That's how vital the arctic sea ice is.

"In the 1970s we had 8m sq km of sea ice. That has been halved.We need it in the summer. It has never decreased like this before".

..."We are on the extreme edge of the models, suggesting that ice loss is happening much faster than the models suggested ," says Stroeve. [emphasis mine]

See the tipping point, folks. Oops, looks like we've lost our footing.